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INSTRUCTION MANUAL
HTM.S4
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Togglewith Singleand
Double Action
SINGLE AND DOUBLE ACTION TOGGLE
Fig. I
Single Action
INTRODUCTION
In the singletoggle mechanismFigure I the links AB and BC are pivoted at B to the connecting
rod BD which is operatedby a crank OD. The link CB pivots about the fixed point C, and A is
attachedto a sliding memberconstrainedto move in a straightline. Any force appliedto BD by
the crank OD is greatly magnifiedat A due to the relatively slight movementproduced at A
comparedwith that of D. The force at A attainsmaximumvaluewhen the links AB andBC are in
line. The pivot B does not travel beyond the line of action drawn between A and C.
Consequentlyits use is normallyrestrictedto machineswhere only a single stroke is requiredto
completethe operation.
Where two strokes are required it is usual to employ the double action mechanismshown in
Figure II. The location of the crank is suchthat the links AB and BC are straightenedbeforethe
crank has completedone half of its revolution. Thus, after the first stroke the links are carried
beyond the centre line and, as the crank continuesto revolve, a second working stroke is
produced. The first and secondstrokesmay be of equalor unequailengthsdependentupon the
position of the crank relative to the line of the straightenedtoggle. Neverthelessthe rightmost
travel of A will be the samefor the two strokes.
As the maximumforce coincideswith the limit of trave~this kind of mechanismcould be usedfor
up-settingthe headof a nail on roundwire rod, or in stonecrushingor embossingmachines.
PROCEDURE
HTM.54. Page 2.
/. January, /995.